This application claims priority under 35 USC 119 of Japanese Patent Application No. 2000-203136 filed in JPO on Jun. 30, 2000, the entire disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates in general to an automatic clutch vehicle, and further, to a clutch control apparatus used in a vehicle such as this, and more particularly, to a clutch control apparatus for automatically engaging and disengaging a friction-type clutch.
2. Description of the Related Art
The applicant, in Japanese Patent Application Laid-Open Publication Nos. 11-245679 and 11-247885, filed patent applications related to an automatic clutch vehicle, in which a friction clutch is automatically engaged/disengaged by a clutch actuator on the basis of an engage/disengage command from a control unit.
The problem is that, in this type of automatic clutch vehicle, clutch disengagement shock occurs when either changing gears or accelerating in a low-speed gear stage is performed. That is, in an automatic clutch vehicle, when the switch for changing gears is turned ON by a driver, the intention to change gears is detected, and automatic clutch disengagement is started. However, when a clutch is suddenly disengaged in a state in which the driver is stepping down on the accelerator, the high torsional torque transmitted to the drive system up until that time is instantly released, clutch disengagement shock occurs, and lurching and other vibrations also take place, making for an unpleasant ride for a passenger. And this also gives rise to the problem of the engine suddenly revving up and the like. Further, among automatic clutch vehicles, there are those that control start of travel so that the clutch engages in accordance with the accelerator being actuated. However, when the accelerator is suddenly released in the clutch engagement process, because the clutch is also suddenly disengaged, similar to hereinabove, there occurs the problems of the torsional torque in the drive system being instantly released and clutch disengagement shock and the like.
An object of the present invention is to reduce clutch disengagement shock brought on by the instant release of torsional torque when changing gears or accelerating in a low-speed gear stage is carried out.
Another object of the present invention is to improve ride-feeling when changing gears or accelerating in a low-speed gear stage is carried out.
According to one aspect of the present invention, there is provided a clutch control apparatus for controlling engagement and disengagement of a clutch via a control unit which comprises a clutch actuator for driving the engagement and disengagement of the clutch, and a control unit for issuing a clutch engage/disengage command to the clutch actuator, this clutch control apparatus further comprising gear-change operation detecting means for detecting a gear-change operation by a driver, gear stage detecting means for detecting the current gear stage of a transmission, and clutch disengagement speed reducing means for setting clutch disengagement speed to low speed when at least the conditions that a gear-change operation by a driver is detected and a transmission is in a low-speed gear stage have been satisfied. In accordance with such constitution, even when a gear-change operation is detected and the clutch is automatically disengaged, if the current gear stage is a low-speed gear stage, disengagement speed is slowed down, and consequently, the clutch is not abruptly disengaged, the sudden release of torsional torque is prevented, and clutch disengagement shock can be reduced.
The apparatus may further include partial engagement detecting means for detecting when the clutch is in a partly engaged state, and the clutch disengagement speed reducing means may reduce clutch disengagement speed when the condition which states that the clutch is in a partly engaged state is added. In the clutch engagement process, high torsional torque is transmitted to the drive system in a partly engaged state, also when the gear is being changed and when the vehicle is starting travel. Accordingly, by reducing disengagement speed when the clutch is disengaged from this state, it is possible to prevent clutch disengagement shock due to the sudden release of torsional torque.
The apparatus may further include accelerator stroke detecting means for detecting the stroke of the accelerator, and the clutch disengagement speed reducing means may reduce clutch disengagement speed when the condition which states that the accelerator stroke exceeds a prescribed value is added. Because high torsional torque is generally transmitted to the drive system when an accelerator stroke is large, by reducing disengagement speed when the clutch is disengaged from this state, it is possible to prevent clutch disengagement shock due to the sudden release of torsional torque.
The apparatus may further include clutch start travel control means for engaging/disengaging the clutch in accordance with the rise/fall of the accelerator stroke when the vehicle starts traveling. In accordance therewith, even if the accelerator is abruptly released in the midst of the accelerator being actuated and the clutch being engaged when the vehicle starts traveling, since the clutch is disengaged at low speed, it is possible to prevent clutch disengagement shock.
In an automatic clutch vehicle incorporating a clutch control apparatus such as this, clutch disengagement shock due to a sudden release of torsional torque at either gear-change or start of travel is eliminated, making it possible to achieve a comfortable ride-feeling. In the present invention, it is possible to realize a so-called selective automatic clutch apparatus, which also enables manual engagement/disengagement.